While superconducting devices such as cables and chokes (inductors) are capable of passing direct current with practically zero losses, they do exhibit considerable AC losses. Described here is a method and apparatus for minimizing these losses in applications where current consists of both a DC component and an AC component. This commonly occurs in rectifier busses, power supplies and power distribution systems.
Currents flowing in networks are commonly categorized as either alternating currents (AC) or direct currents (DC). The notion of direct current is misleading, however, and in practice one actually means a current with frequency components below some lower cutoff frequency, usually below the first dominant harmonic of the current. This invention separates these currents in cables and chokes in such a way that one can take advantage of the benefit of superconducting technologies, which work best at very low (DC) frequencies.